Instead of registering a cleanup handler to just destroy an independent pool,
just create a subpool. This avoids a possible ordering problem when the pools
are only cleaned up at exit or fork time.

* subversion/svnserve/logger.c
  (cleanup_logger): Remove function.
  (logger__create_for_stderr,
   logger__create): Create subpool instead of registering cleanup handler.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1558416 13f79535-47bb-0310-9956-ffa450edef68